The present invention relates generally to an apparatus for processing fruit in multiple layers, and more particularly to improved tanks used for processing fruit in multiple layers in accordance with the method disclosed in U.S. Pat. No. 6,159,527, the subject matter of which is incorporated herein by reference thereto.
In the follow description and claims the term fruit should be interpreted to include other vegetable products, such as, but not limited to, celery, carrots, vanilla beans, and/or broccoli.
In U.S. Pat. No. 6,159,527 a method and apparatus are disclosed for infusing fruit with sugar by flowing an infusing liquor containing dissolved sugar and fruit juice through the processed fruit. The infusing liquor has strata of progressively higher concentrations of sugar. The flow rate is controlled so that the strata with the progressively higher concentrations of sugar only just slightly exceeds the sugar content of the fruit being infused. Thus, the infusing is done at a rate slow enough so that as fruit juice leaves the fruit it will be replaced with sugar during an osmotic transfer without causing osmotic dehydration. This slight differential in sugar contents is necessary in order to prevent osmotic dehydration. This infusion continues until the fruit reaches saturation. At saturation, the liquid inside the fruit gels, firming the fruit so that the infused fruit has a firmness similar to the firmness of the raw fruit.
Before infusion, fruits may be initially processed to condition it for infusion. The initial processing of hard fruits, such as cranberries, may include pressing it, to remove a desired quantity of juice, typically about 50-80% of the fruit juice. (The amount of juice removed may be that necessary to leave a soluble acid concentration substantially equal to that desired in the fully infused fruit.) In addition, care is exercised during pressing so that most of the cells within the fruit are not ruptured. After the initial pressing of hard fruits, the fruit is plumped up (or plumped) by replacing the juice which has been pressed out with other fluids by immersing the fruit in a mixture of water, juice and sugar. After this step has been completed, the fruit is then infused in the manner set forth above. The invention which includes pressing of a hard fruit is more fully set forth in applicant""s U.S. Pat. No. 6,159,527.
The operation of the process is a continuous batch process. As shown in the various FIGS. of the patent, four tanks or vats 10, 12, 14, and 16 are used for infusing fruit, these tanks being interconnected with suitable plumbing to establish a flow path from tank 10 to tank 12 to tank 14 to tank 16 and back to tank 10. In addition, a bleed or overflow tank 18 is also provided. Fresh fruit (which may be at room temperature or frozen, and which may be processed or unprocessed fruit) is placed in the first tank in the series, and then fresh fruit is introduced sequentially in each subsequent tank in the series after suitable time intervals. Thus, at the beginning of a first time interval, fresh fruit is loaded into tank 10, at the beginning of a second time interval fresh fruit is loaded into tank 12, and so on. Fresh fruit is always loaded into a tank just before it is processed to avoid premature spoilage of the fruit.
The above identified patent describes initial processing and also continuous batch processing. In this regard, it should be noted that the initial processing is for the purpose of building up a stratified column of infusing liquor from the initial infusing liquor, which consists of a fruit juice or fruit juice concentrate which has been fortified with additional sugar if necessary to bring it to a high sugar content, typically 70 Brix. The stratified column, after the initial process has been completed, is formed of superimposed layers of liquors of differing sugar content, which vary from a Brix content equal to the initial infusing liquor at the downstream end to the Brix content of the juice which is to be extracted from the fruit at the upstream end. Preceding the upstream end after the initial processing has been completed is a column of pure fruit juice. Upstream and downstream references are derived from the fact that the infusing liquor is moved upwardly through the infusing tank during infusing. This is because the liquor with the higher sugar content has a higher specific gravity than the liquor with lower sugar content.
As the initial processing may vary from fruit to fruit, the processing of a soft fruit such as strawberries is described initially. At the start-up of infusing, and during a first time interval or cycle, a first batch of whole strawberries, which have been frozen in a conventional manner, are taken from a freezer and placed in thin layers in infusion vessel 10 shown in the aforementioned patent. If desired the strawberries may be sliced and diced after tempering and before infusion. Strawberries are infused best if the layers are not greater than 7.5 mm or 3 inches deep. For this discussion, it will be assumed that the sugar content of the strawberries is 12%, and therefore, the sugar to water weight ratio will be at or slightly below 12% (commonly referred to in the industry as Brix.) The first batch of frozen berries (which are frozen at about 5xc2x0 F.) are thawed with juice for a few moments after the tank 10 has been filled, the juice having been warmed to 140xc2x0 F. The fruit is covered with a screen which may be secured to tank 10 in any conventional manner. The screen secures the fruit within the tank and prevents it from floating downstream to the next tank with the flow of infusing liquor from one tank to the next.
The thawing time is determined by observing the tank. Initially, when warm water thawing liquid is introduced into the tank frost will form on the outside of the tank. When the tank is no longer frosty, the berries will have become sufficiently thawed to be infused. This thawing time period will be noted.
Next, during a second time interval an infusing liquor, which consists of a fruit juice or fruit juice concentrate which has been fortified with additional sugar if necessary to bring it to 70 Brix, is now slowly introduced into the bottom of tank 10 to progressively infuse the berries from the bottom up. When the infusing liquor is introduced into tank 10, suitable valves are opened to permit thawing liquid to flow from tank 10 to a holding tank. As the front of the 70 Brix infusing liquor moves slowly up through the berries in tank 10, stratification of the infusing liquor will occur. Thus, the initial strata of the 70 Brix infusing liquor will be diluted as fruit juice leaves the fruit through osmosis, until the leading downstream strata is essentially pure fruit juice with a Brix just slightly greater than that of the fruit, for example just above 12 Brix if the fruit has a Brix of 12. Infusing liquor which has had its Brix reduced to that of the fruit is now considered to be a juice product. Normally this full dilution of the infusing liquor will not occur in the first tank during the second time interval, but in the second tank during a third time interval. Succeeding strata of the infusing liquor (as measured in the upstream direction) will have progressively increasing Brix up to the initial Brix of the infusing liquor. Initially, the pump controls the flow rate of infusion liquor into the tank 10. It may take as little as 3 hours or as long as 12 hours or longer to fill the tank with infusion liquor, the time being established by the particular fruit and any initial processing it may have received. Thus, if osmosis is fairly rapid in a particular fruit, the tank may be filled more quickly, for example, in three hours. However, if osmosis is slow for a particular fruit, the tank may be filled more slowly, for example 12 hours. In any event, the next tank will be filled with a layer of berries and a thawing liquid a sufficient length of time before the first tank becomes completely filled, so that the berries in the second tank become thawed before the first tank becomes completely filled with infusion liquor.
During a third time interval or cycle, the 70 Brix infusing liquor is still introduced into tank 10, and suitable valves are opened to permit the front of the infusing liquor to move from tank 10 to tank 12, the flow being controlled by separate pumps. Meanwhile, suitable valves are opened to permit the thawing liquor in tank 14 to flow into holding tank 36. Before the end of this time interval new berries are introduced into tank 16 and held in place by a screen for a sufficient length of time to thaw the layer of berries. By the end of the third time interval, full, or substantially full, stratification of the infusing liquor has been achieved, and there will be no danger, or virtually no danger, of osmotic dehydration of the fruit in tanks 14 and 16, as the stratified column of infusing liquor is caused to flow into these tanks, although there may have been some osmotic dehydration in tank 12, and there was osmotic dehydration to the berries in tank 10 during start-up. The batch process will now be continuously operated.
The theory of operation for creating a stratified infusion liquor is set forth in the U.S. Pat. No. 6,159,527 and will not be repeated here.
In the design shown in aforementioned U.S. patent, the stratified column of infusing liquor passes through all of the berries in tank 10 and proceeds through tanks 12, 14, 16, and then back to tank 10 under the successive control of various pumps. Each tank holds approximately 3 inches of strawberries below the screen, plus an additional reservoir of fluid above the screen. The strawberries, for example in tank 10, reach saturation after three cycles. Although strawberries reach saturation at 55 Brix, the Brix of the infusing liquor is preferably 70 Brix, since a 70 Brix solution will not spoil over an extended period of time. After infusion is completed in any tank, the strawberries are removed from the tank for further processing. After start-up, a column of substantially pure fruit juice will precede the stratified column. Part of this column of substantially pure juice is apportioned off to a juice tank for further juice processing. Thus, a substantial juice byproduct is obtained by this infusion process.
During continuous operation, differing aspects of the invention are occurring simultaneously in each of the respective tanks. After start-up, during the continuous batch processing, the stratified liquor which is used to treat the fruit has a length of about 1{fraction (1/2 )} tanks. For example, at the beginning of cycle n, fruit in tank 10 has become substantially fully saturated, and tank 10 is ready to be emptied. At this time the infusing liquor in tank 10, top and bottom, is at 70 Brix, and in the next 1{fraction (1/2 )} tanks (12 and 14) it is stratified. Thus, the sugar concentration in the bottom of the next tank 12 is 70 Brix, and the sugar concentration at the top of tank 12 is in the range of 25-30 Brix. At this time the infusion liquor in the bottom half of tank 14 is partially stratified, the sugar concentration in the bottom being 25-30 Brix, and this stratification continues to about midway up the tank, where the Brix content drops to an amount just slightly more than that of the berries.
Cycle n commences when the introduction of infusion liquor is switched from tank 10 to tank 12. Cycle n may be as long as 12 hours or as little as 3 hours. After the commencement of the cycle, tank 10 must be dumped, and it must be refilled with fresh berries and thawing liquid, the fresh berries being secured in place with screen 40. Initially, during a first time period of cycle n, tank 10 is isolated from the other tanks 12-16 by closing off suitable valves (not numbered). During this same time period, flow from the infusion liquor tank is directed to the bottom of tank 12 by closing and opening suitable valves. In addition, the flow from tank 14 is directed to overflow tank 18 by opening a suitable valve. These valves may be manually operated, or they may be solenoid operated. At the conclusion of the first time period of cycle n, infusing liquor will be pumped into tank 12, and the front of the infusing liquor, which is pure fruit juice, will be pumped into overflow tank 18. The flow rate is adjusted to maintain the length of the stratified column to 1{fraction (1/2 )} tanks. To this end, refractometers are provided in the fluid lines which convey infusing liquor from the top of one tank to the bottom of the next tank, the refractometers measuring the Brix of the liquor as it exits a tank. If the Brix is too high, during cycle n the flow rate is slowed up. If the Brix is too low, the flow rate is increased.
Once tank 10 has been isolated and flow has been established through tanks 12 to 14, during a second time period of cycle n, the berries and infusing liquor surrounding the berries in tank 10 are dumped for further processing in the manner set forth below. Subsequently, tank 10 is refilled with fresh berries and thawing liquid. In addition, the berries are secured in place with a screen.
During the next cycle n+1, tank 12 is isolated, the output from tank 14 is connected to tank 16. Tank 12 will now be dumped and refilled in the same manner as tank 10.
From the above discussion, the continuous operation may be generalized as follows. At any given time, during continuous operation, one tank in the process will be isolated out of the cycle for emptying and subsequent refilling. The tank immediately downstream of the isolated tank will be receiving only pure 70 Brix infusing liquor, and the fruit within it will be approaching saturation. A third tank, which is immediately downstream of the second tank, will be receiving stratified liquor pumped from the second tank. Finally, a fourth tank, which is immediately downstream of the third tank, may be isolated containing only thawing liquid and fruit, or it may be receiving stratified liquor from the third tank. Excess fluid from a downstream tank will be pumped into a holding tank until it is used later on. While 70 Brix has been used in the example set forth above, the infusion liquor could be at other Brix, for example 72.
At the conclusion of processing the fruit is subject to further processing. Such processing includes washing on a screen and drying to a suitable water activity level.
In the forgoing example taken from the above mentioned patent, each tank holds a layer of strawberries which is only about 3 inches deep. If the layers are more than 3 inches thick, the buoyancy of the strawberries are such that the berries on top tend to be crushed by the berries below. Furthermore, it is necessary to have tanks of very large diameters in order to secure a desired throughput of processed fruit.
It is an object of the present invention to provide an apparatus which overcomes disadvantages of the prior apparatus.
More particularly, it is an object of the present invention to provide an apparatus for processing fruit in multiple layers which will minimize labor and automate as much as possible.
It is a further object of the present invention to produce a better fruit product by processing the fruit in very thin layers
It is another object of the present invention to provide an apparatus for processing fruit in thin layers, which is particularly advantageous for infused fruit with sugar.
Another object of the present invention is to make an apparatus which meets customer requirements of throughput, as well as minimize floor space.
It is yet another object of the present invention to provide an apparatus which can be cleaned in place.
A still further object of the present invention is to provide an apparatus which will minimize convection mixing of the stratified column of infusing liquor.
These and other objects of the present invention will be apparent to those skilled in the art after a consideration of the following detailed description taken in conjunction with the accompanying drawings in which a preferred form of this invention is illustrated.